Hyperextension of the knee is a common injury among athletes across a wide variety of sports. The severity of the condition will vary based on the cause of injury and each individual athlete’s body. In most cases, hyperextension of the knee will have obvious symptoms including swelling, reduced range of motion, sharp localized pain, and instability on the affected leg.
Hyperextension occurs when the knee joint is forced to extend beyond its normal range of motion. In these instances, a large amount of stress is put upon one or more of the four major ligaments of the knee joint:
- The medial collateral ligament (MCL)
- The lateral collateral ligament (LCL)
- The anterior cruciate ligament (ACL)
- The posterior cruciate ligament (PCL)
Hyperextensions of the knee can occur to anyone, but are frequently the result of athletic injuries. Athletes who compete in contact sports like football, soccer, or lacrosse are most commonly affected. Other sports, like skiing, may cause the knee joint to suddenly be moved out of position and cause this injury.
Causes of Knee Hyperextension
When too much weight or pressure forces the knee into extension, the joint can extend further than its true range of motion, causing soft tissue damage, swelling, and potentially tears or strains of the MCL, LCL, ACL, or PCL. Common causes of knee hyperextension include:
- Pushing the femur or patella over the tibia and placing excess stress upon one or more of the major ligaments within the joint. This sort of impact might be experienced by a basketball player stopping unexpectedly and placing all of their weight on one leg to do so.
- Unexpected impact to the front of the knee, causing backward movement of the knee joint, may cause the ACL to strain or tear. This sort of impact would occur in traumatic physical situations, such as a football player being tackled by the legs or a soccer player being slid into.
The method by which a knee hyperextension is caused can predict the severity of the condition. In minor cases, an athlete will notice small amounts of pain or swelling. In traumatic injury, however, hyperextension of the knee may also cause damage to the surrounding ligaments, cartilage and soft tissues.